Add multi-tenant cloud mode: self-serve purchase, credit metering, core-decoupling

Introduces RECAP_MODE=multi alongside single-mode self-host:
- Tenant auth + accounts (magic-link via System SMTP), per-tenant credit pool,
  anonymous trial minting with per-IP/-64 caps
- Self-serve Pro/Max purchase: inline Lightning (BTCPay) + card (Zaprite),
  prepaid 30-day periods, expiry-reminder emails
- Core-decoupling: relay owns cloud tier/expiry keyed by Recaps user-id
- SQLite (better-sqlite3) schema for multi-mode; filesystem unchanged for single
- StartOS actions/versions through 0.2.155

startos/versions/v0.2.84.ts

@@ -0,0 +1,12 @@
+import { VersionInfo } from '@start9labs/start-sdk'
+
+export const v_0_2_84 = VersionInfo.of({
+  version: '0.2.84:0',
+  releaseNotes: {
+    en_US: 'Trial credits are now LIFETIME per IP, not per-day. A visitor who clears cookies can no longer reset their trial allowance by waiting 24 hours — the operator-set cap applies once and forever per IP. Existing operator config preserved: the legacy field name keeps working as a read-only alias. Operator can tune via "Set Trial Cookies per IP (Lifetime)" StartOS action. Also: admin users no longer get a stray tenant_credits row seeded at signup (they bill the operator pool directly, not a local balance). Polished password input styling on /auth.html so it matches the email field. Added Open Graph + Twitter Card meta tags so iMessage / Twitter / LinkedIn / Discord link previews render a Recap branded card when the URL is shared.',
+  },
+  migrations: {
+    up: async ({ effects }) => {},
+    down: async ({ effects }) => {},
+  },
+})